I have been experimenting to see how much of the Firefox GUI is actually required vs that which is just fluff. As requested by @tsuki_chama, here is a list of plugins and config I am using.
1. Start with Firefox 4. On Ubuntu Lucid / Maverick you can use “sudo apt-add-repository ppa:mozillateam/firefox-stable” and then do an upgrade.
3. Grab the Firefox extension called “Hide Caption Titlebar Plus” and configure as desired. To be even more skimpy you can leave off the min/max/close buttons and just use alt+space.
4. Compiz is needed to remove the window border (idea stolen from here). Edit the settings for the “Window Decoration” pluging and set “Decoration windows” field to “any & !(role=browser & class=Firefox)”.
bonus: Add the Firefox theme Grey and Black.